After an hour and a half, and three attempts, they pushed the enemy to the brink of disaster (red indicator), but still couldn't win. Just as I was about to start training my characters, someone suggested trying it on auto-battle in the comments.
"There's no way they can win," I thought, watching as they won with almost no danger whatsoever.
The level-up melody, "Terereretettete♪," evoked a strange mix of emotions, and then Buzz summoned a banana, but couldn't eat it himself (partly due to the auto-battle), creating a scene where I almost felt sorry for Buzz... (It was incredibly funny lol).
Unfortunately, they didn't defeat the final boss, so it wasn't the final episode, but there was quite a bit of progress and twists and turns.

Momoko Kashiwagi - Dragon Quest 2 Remake: Hargon's Temple VS Pazuzu | Wild's post